A method for making a folded fin for a heat sink comprises the steps of: preparing a metal plate; clamping the metal plate with three forming jigs in an initial position, the lower jig portion of the second forming jig having a tapered end; actuating the second forming jig to upwardly move toward the first forming jig at a specified angle and the third forming jig to horizontally move toward the first forming jig to a second position where a portion of the metal plate between the forming jigs has been bent into a pair of symmetrically inclined sections; and actuating the lower jig portion of the second forming jig to downwardly move away from the metal plate at a specified angle, and the third forming jig and the upper jig portion of the second forming jig to continue moving toward the first forming jig to a final position where the pair of symmetrically inclined sections of the metal plate has been bent double thereby forming a folded fin. A machine is disclosed to make the folded fin by the method disclosed above.